Drum closure system: closing ring, crimping machine and method of use

ABSTRACT

An improved drum ring and apparatus for forming the ring during sealing of a drum utilizes a depending open leg having an initial diameter larger than the head of the drum to be sealed and a cover associated therewith. The open leg is deformable about the drum cover and drum body curl by a segmented forming tool to seal said cover to said drum in a compressed condition.

BACKGROUND OF THE INVENTION

This invention relates to split locking rings, and assembly methods forthose locking rings, used for closure of shipping drums or barrels withremovable covers.

Current methods for affixing removable covers and sealing gaskets toshipping drums make use of a container design which includes at its openend a drum curl of circular section, a removable cover having an upwardand outward protruding flange of similarly arcuate shape as the drumcurl, and a gasket suitable for compressing between the curl and cover.Contact and sealing of the curl and cover with the compressible gasketis facilitated by the use of a metal or plastic ring. The ring utilizesany of a variety of angled or tapered “U” or “V”-shaped sections openingradially inward toward the center of the drum. The inside surfaces ofthe ring simultaneously engage the bottom of the drum curl and the topof the drum cover tangentially. The ends of the locking ring are drawncircumferentially toward one another through the use of a threadedfastener or an over-center type locking buckle, thereby forcing the ringfurther over the drum curl and cover, and forcing these two members evercloser together, trapping and compressing the sealing gasket betweenthem, thus closing the drum.

SUMMARY OF THE PRESENT INVENTION

It is an object of the present invention to provide an improvedcombination closing ring design, and a device and system for assemblingthe closing ring onto the drum, that results in increased packagereliability, and increased package manufacturing efficiency.

These and other objects of the present invention are accomplishedthrough the use of a drum ring which is only partially formed prior toplacement on the drum and a drum sealing device the completes theformation of the drum ring on the drum and lid during the sealingprocess.

These and other objects and advantages of the invention will becomeapparent from the following detailed description of the preferredembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

An apparatus for crimping rings on drum heads—embodying the features ofthe present invention is depicted in the accompanying drawings whichform a portion of this disclosure and wherein:

FIG. 1 aa is a plan view of the prior art desired drum closure.

FIG. 1 b is a sectional view of the prior art drum closure assembly atfit up.

FIG. 1 c is a sectional view of the prior art drum closure assembly atclosure;

FIG. 1 d is a plan view of the prior art drum closure joint;

FIG. 1 e is a sectional view of the prior art drum closure assembly andcompression tool;

FIG. 2 a is a plan view of the present invention drum cover;

FIG. 2 b is a sectional view of the drum closure assembly at fit up;

FIG. 2 c is a sectional view of the drum closure assembly atcompression;

FIG. 2 d is a sectional view of the drum closure assembly at closure

FIG. 2 e is a plan view of the drum closure bolt joint of the presentinvention;

FIG. 3 a is perspective view of the upper forming tool;

FIG. 3 b is a sectional view of the upper forming tool and drum closureassembly at fit up;

FIG. 3C is a sectional view of the upper forming tool and drum closureassembly at compression;

FIG. 4 a is a perspective view of the lower form tool retracted;

FIG. 4 b is a perspective view of the lower form tool retracted;

FIG. 4 c is a sectional view of the lower form tooling condensed;

FIG. 5A to 5L is a sequential series showing movement of the majorcomponents of a closure machine incorporating the principles of thepresent invention;

FIG. 6A is an elevational view of the major components of a closuremachine prior to compression of a drum closure assembly

FIG. 6 b is an elevational view of the major components of a closuremachine with the gasket compressed by the lower hydraulic ram;

FIG. 6C is an elevational view of the major components of a closuremachine with the lower form tool condensed;

FIG. 6D is an elevational view of the major components of a closuremachine at closure;

FIG. 6E is a sectional view of the major components of a closure machinein accordance with this invention;

FIG. 7 is a sectional view of the upper form tool with the drum gasketin compression; and

FIG. 8A to 8D show an alternative embodiment for crimping the ring inplace.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the Figures for a clearer understanding of the invention,prior art affixation of removable covers and sealing gaskets to shippingdrums make use of a drum 100 which includes at its open end a drum curl101 of circular section, a removable cover 103 having an upward andoutward protruding flange of similarly arcuate shape as the drum curl,and a gasket 102 suitable for compression between the curl and cover asshown in FIG. 1C. Contact and sealing of the curl and cover with thecompressible gasket is facilitated by the use of a metal or plastic ring10. The ring 10 utilizes any of a variety of angled or tapered “U” or“V”-shaped sections opening radially inward toward the center of thedrum as shown in FIGS. 1B and 1C. The inside surfaces of the ring 10simultaneously engage the bottom of the drum curl and the top of thedrum cover tangentially as shown in FIG. 1B. The ends of the lockingring are drawn circumferentially toward one another through the use of athreaded fastener 15 passing through threaded 11 and non-threaded metallugs 12 affixed to the ends 13, 14 of the ring, thereby forcing the ringfurther over the drum curl and cover, and forcing these two members evercloser together, trapping and compressing the sealing gasket betweenthem, thus closing the drum as shown in FIG. 1C.

In the description of the preferred embodiment like numbers will be usedfor components that are consistent with the prior art. It may be seen inFIGS. 2B and 2A, that in the present invention, the closing ringassembly comprises of a metal ring 10 of approximate “L”-shape, threaded11 and non-threaded metal lugs 12 affixed to the ends 13 of the ring,and a bolt 15 of diameter and threads to match the lugs. Ring 10includes a top leg 16 of the “L” designed in accordance withconventional practice, its length, angles, bends and features selectedto provide good package performance in tests for hydrostatic pressureand vertical drop. In as much as ring 10 is intended to be formed to afinal configuration when used in conjunction with a drum 100, an openleg 17 of ring 10 may be straight, slightly angled, or curved, dependingon the desired final shape after forming, and compatibility with thetooling selected for use in the forming operation. The diametergenerated by the configuration of open leg 17 must be such that when thering assembly is drawn to minimum circumference, the ring still may beeasily positioned over the top of a loosely assembled drum curl 101,gasket 102, liners where applicable, and cover 103 combination as shownin FIG. 2 a. The length of open leg 17 is determined and selected suchthat upon completion of the forming operation onto the specific drum forwhich the ring is designed, a gap ranging from 1/32″ to ⅛″ is maintainedbetween the end of leg 17 and drum body 100 as shown in FIG. 2D.

The assembly mechanism embodying this invention includes solid upperform tooling 20 shown in FIG. 3A to 3C, segmented lower form tooling 30as illustrated in FIG. 4A to 4D* as well as associated actuators andcontrols required for the purposes of transforming “L”-shaped ring 10into a “U” or “V”-shaped ring 10, i.e. forming, closing or crimping thering 10 onto the drum as exemplified in FIGS. 5A to 5L.

The configuration of upper form tooling 20 is specific to eachapplication in that its diameter and its annular profile seat or contourprecisely matches top leg 16 of ring 10, selected as described above,for the package in question. During forming of the open leg 17, theupper form tooling 20 is responsible for holding the closing ring 10rigidly in place and on center with the drum, for maintaining theintegrity of the profile of top leg 16, and for transmitting an axialforce to the package assembly which compresses together all thecomponents of the package including drum curl 101, drum liners, drumgasket 102, and drum cover 103.

Lower form tooling 30 cannot be solid since at the completion of thering forming operation, its inside diameter will by necessity be smallerthan that of the drum body curl 101 as well as the outside diameter ofthe ring. Instead it must be sectional, so that it starts at a diameterlarge enough to envelop the outer diameter of the ring's open leg 17,form it to a diameter which creates the gap described earlier betweenring 17 and drum 100 body, and then return to a diameter large enough toallow it to be withdrawn from the diameter of the drum and completedring. Like upper form tooling 20, the configuration of the lower formtooling is specific to each application. Its minimum interior diameterand profile precisely match that of the formed ring in its completedconfiguration thus each segment 31 has a die face 32 formed on its innerprofile for engagement with outer leg 17. Two methods are disclosed asexemplary for moving lower form tooling 30 and the closing ring open leg17 from its initial shape to its finished, formed shape, ie. open leg 17may be either swaged or crimped into shape, with the method chosen tobest suit the desired finished shape for each specific application

The process for using this ring and ring closing or forming mechanism,hereafter referred to as the closure system, are described as follows:Ring 10 is manufactured in its “L”-shaped configuration. Lugs 12 areattached to ring ends 13, 14. Bolt 15 is installed into the lugs andtightened to its final engagement. This assembly step represents thefirst innovation and improvement realized through the use of thisclosure system. Conventional rings require that the bolt cannot beassembled until the ring is positioned onto the drum. Pre-assembling thebolt to its final engagement overcomes the following disadvantages ofthe prior art:

1) When not subjected to the interference and awkwardness generated bythe body of a drum, bolt 16 insertion may be properly aligned and thusinstalled faster and more accurately. When installing the bolt onconventional rings, cross threading of bolt to lug is a persistentconcern as shown in FIG. 1D.

2) Bolt 15 may be tightened to a mechanical preload, as is the commonpractice for all bolted joints. Conventional rings, when bolted at finalassembly, leave a gap “D” in the mechanical joint that prevents theproper preloading of the bolt, and induces bending moment stresses anddistortion “

” into the bolt again as show in FIG. 1D.

In the present invention, with bolt 15 preloaded, and lugs 12 thus heldtogether as a solid mechanical entity, the loading transmitted from thelugs 12 to the ring 10 is one of almost pure shear. No bending momentsare induced on the joint from lug 12 to ring 10 and the joint is thusstrengthened considerably.

At fit-up, drum 100, drum liners if required, gasket 102, and cover 103are all assembled and ring 10 is placed over drum cover 103.Alternately, ring 10 may be pre-assembled onto a cover 103, or onto acover and permanently affixed gasket, and then placed onto a drum 100.In either case, this assembly step represents the second innovation andimprovement realized through the use of this closure system. Becauseconventional rings are, at initial assembly, smaller at their openingthan the combined heights of the drum curl, liners, gasket and cover,the conventional ring has little ability to stay in place on the drum.Not until the cover and gasket are compressed, allowing the drumassembly to “sink” into the “U” or “V” of the ring, will the ringnormally stay on the drum. Furthermore, conventional rings have littleability to assist in the alignment of the drum components. However ring10 described in this invention successfully facilitates both of thesegoals. Top leg 16, which is, at assembly, already secured with adiameter smaller than that of cover 103, prevents the ring 10 fromsliding off cover 103 and down around the body of the drum 100 to thefloor. Open leg 17 of ring 10 simultaneously capture cover 103, gasket102 and curl 101 of the drum assembly and prevent their movement offcenter one from another. Thus fit up may occur well be for machine entryas shown in FIGS. 5A & B and 6A.

The first step in the closure process is to compress thedrum/gasket/cover/ring assembly to its desired finished height as shownin FIGS. 5C & D and 6B. This step represents the third innovation andimprovement realized through the use of this closure system. Withconventional rings, the gasket and liner compression forces are appliedto the drum cover and transmitted through the cover to the gasket in anoffset path. This is because the top surface of the cover must be leftvacant to accept the ring as it moves radially into place. The amount offorce that can be applied is limited by the ability of the cover totransmit that force. However the ring and mechanisms described by thisinvention allow more direct application of the required compressiveforce. The upper form tooling provides an annulus for the application ofthe force directly to the ring 10; the ring transmits the force to cover103; cover 103 transmits the force to the gasket 102; gasket 102compresses against drum curl 101, all in a straight line through thebody of ring 10 and cover 103 as shown in FIG. 7. Thus, a substantiallyhigher compressive force, limited only by the strength of the drum curl101, may be applied to compress the gasket and other components to thedesired height.

With all components compressed to the desired finished height as inFIGS. 5 c and 6 b, ring 10 is then mechanically formed, i.e. closed. Inapplications where the swage method is employed, segments 31 of lowerform tooling 30 come together to form a continuous die with a small gapleft at one quadrant to accommodate lugs 12 as shown in FIGS. 4B, 5E,and 6C. This Swage Die is then moved axially toward upper form toolingas shown in FIGS. 5 f-5 i and 6 d . . . As open leg 17 of the ring 10contacts the combined die face 32 of lower form tooling 30, leg 17 isswaged inward toward the drum curl 101 creating a conventional “U” or“V”-shaped cross section. The distance inward that the edge of open leg17 travels, and thus the closed dimension of the ring 10, is establishedby the vertical distance the lower form tooling 30 is allowed to traveland the profile of die face 32.

This step represents the fourth and fifth innovations and improvementrealized through the use of this closure system. Because the finaldimensions of the Ring's “U” or “V”-shaped cross section can becontrolled at assembly, slight variations in the compressed height ofthe other components may be compensated for. Two drums differing only bythe use or absence of a 50 mil drum liner for example, can use the samesplit locking ring. The ring on the drum without the liner is simplyclosed to an appropriate, smaller dimension.

Furthermore, because ring 10 is closed by forming it in the samedirection, i.e. radially, as the compressive force that keeps the drumsealed in the completed package, the reliability and uniformity of thefit of the ring to the drum and cover is enhanced. With a conventionalring that is tightened circumferentially, the circumferential movementof the ring that reduces its diameter and increases its compressiveforce is resisted by the friction generated between the ring, and thecover and drum curl. The tighter the ring is pulled, the higher thecontact forces between the ring and the cover and curl. And the higherthe contact forces, the higher the frictional resistance becomes. Thering becomes its own worst obstruction to proper tightening. In someareas, typically near the lugs, the conventional locking rings fullyengage the drum cover and curl. In other areas however, the frictionalforces can prevent the conventional locking ring from fully engaging thedrum components. Inadequate engagement results in lowered clampingforces at the curl/gasket/cover joint. In the closure system describedby this invention, no frictional forces are created as the Open Leg isformed. In fact, no forces resisting the closing action are encounteredother than the bending of the ring material which is uniform,predictable, and easily controlled by the form tooling and the actuators33 that move it as shown in FIG. 6. With the ring forming complete,lower form tooling 30 retracts and expands to allow removal of thecompleted drum package as shown in FIGS. 5J to 5L.

In applications where the crimp method is employed, the segments 31 oflower form tooling 30 are pivotally mounted to upper tool 20 and cometogether to form a continuous die face 32 as open leg 17 is formed,rather than before as illustrated in FIGS. 8A to 8C. The movement ofsegments 31 is a rotational combination of the axial and radialdirections and may be effected by actuations cooperatively attachedthereto. The result is the same. The ring is formed inwardly against thedrum curl in the radial direction, free from frictional forces createdby the force of the ring sliding against the drum cover and drum curl.And the degree of closure is controlled by the distance the crimpingsegments are allowed to rotate.

A split, bolted locking ring that can be preassembled in mass productionat a factory level, final formed in place using an automatic machine asthe drum is produced, and then re-used like a conventional locking ringby the drum purchaser, represents a significant innovation in theshipping container industry. Manual closing of conventional splitlocking rings requires 15 to 20 seconds per package and may require twopeople. The exemplary machine pictured requires a maximum of one personto operate and final assembles a drum in approximately 8 seconds. Thecombination of the locking ring configuration and the forming equipmentput forth in this invention successfully automates this assemblyprocess, and simultaneously improves the reliability of the open headcontainer package

It is to be understood that the form of the invention shown is apreferred embodiment thereof and that various changes and modificationsmay be made therein without departing from the spirit of the inventionor scope as defined in the following claims.

1. An improved ring construction for use in a drum closure assemblywherein the drum closure assembly includes a drum body curl, and a drumcover, said ring construction comprising and annular metallic striphaving a generally L shape defined by an upper leg and a depending openleg, said upper leg partially overlying said drum cover and saiddepending leg extending below said drum body curl.
 2. An improved ringconstruction as defined in claim 1 wherein said strip has a first andsecond ends which substantially abut at a joint.
 3. An improved ringconstruction as defined in claim 2 wherein said open leg defines aninner diameter greater than the diameter of said drum cover and saiddrum body curl.
 4. An improved ring construction as defined in claim 3wherein said open leg is formable to conform to the shape of said coverand drum curl.
 5. An improved ring construction as defined in claim 2wherein said strip has a threaded lug affixed at said first end and aunthreaded lug affixed at said second end and further comprising athreaded bolt passing through said unthreaded lug and engaging saidthreaded lug to fix said strip and lugs in rigid mechanical engagementbefore and after drum closure.
 6. An apparatus for sealing a drum usingthe ring construction of claim 1 comprising: an upper form toolingcomprising an annular seat overlying said upper leg and a segmentedlower form tooling comprising a plurality of segments movable radiallyand vertically relative to said upper forming tool.
 7. Apparatus asdefined in claim 6 wherein each segment had defined thereon a die facefor engagement with said open leg such that said open leg is formed bysaid face into conforming relationship with said drum curl and cover. 8.Apparatus as defined in claim 7 wherein said drum closure assemblyincludes a gasket intermediate said drum curl and said drum cover andsaid apparatus further comprising an actuator for compressing said topform tooling, said upper leg, said drum cover, said gasket and said drumcurl to a desired position.
 9. Apparatus as defined in claim 8 furthercomprising at least one actuator operatively connected to said lowerform tooling to urge said segments of said lower form toolingselectively between a retracted position and a condensed position. 10.An apparatus for sealing a drum wherein said drum has an open end withan annular drum curl formed thereon and a drum cover overlying open endand said drum curl, comprising: an upper forming tool defining a seatagainst which said drum cover and portion of a drum ring overlying saiddrum cover abut, a plurality of segments defining lower form toolingselectively movable between a retracted position and a condensedposition wherein said segments each include a die face for engaging aportion of said drum ring extending below said drum curl for formingsaid drum ring to seal said drum.